CN101959820A - TiO2-containing silica glass and optical member for EUV lithography using high energy densities as well as special temperature controlled process for its manufacture - Google Patents

TiO2-containing silica glass and optical member for EUV lithography using high energy densities as well as special temperature controlled process for its manufacture Download PDF

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CN101959820A
CN101959820A CN2009801065551A CN200980106555A CN101959820A CN 101959820 A CN101959820 A CN 101959820A CN 2009801065551 A CN2009801065551 A CN 2009801065551A CN 200980106555 A CN200980106555 A CN 200980106555A CN 101959820 A CN101959820 A CN 101959820A
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tio
temperature
glass
silica glass
sio
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小池章夫
斋藤健太
邵龙
岩桥康臣
菊川信也
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AGC Inc
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Asahi Glass Co Ltd
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    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/14—Other methods of shaping glass by gas- or vapour- phase reaction processes
    • C03B19/1453—Thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering
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    • C03B19/00—Other methods of shaping glass
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    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
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    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
    • H01L21/0271—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers
    • H01L21/0273—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers characterised by the treatment of photoresist layers
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    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
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    • C03B2201/23—Doped silica-based glasses doped with non-metals other than boron or fluorine doped with hydroxyl groups
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
    • C03B2201/40—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn
    • C03B2201/42—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn doped with titanium
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2207/00—Glass deposition burners
    • C03B2207/70—Control measures
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
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    • C03B2207/80—Feeding the burner or the burner-heated deposition site
    • C03B2207/81—Constructional details of the feed line, e.g. heating, insulation, material, manifolds, filters
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2201/00—Glass compositions
    • C03C2201/06—Doped silica-based glasses
    • C03C2201/20—Doped silica-based glasses containing non-metals other than boron or halide
    • C03C2201/23—Doped silica-based glasses containing non-metals other than boron or halide containing hydroxyl groups
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2201/00—Glass compositions
    • C03C2201/06—Doped silica-based glasses
    • C03C2201/30—Doped silica-based glasses containing metals
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    • C03C2201/42—Doped silica-based glasses containing metals containing transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn containing titanium
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    • C03C2203/00—Production processes
    • C03C2203/40—Gas-phase processes
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    • C03C2203/44—Gas-phase processes using silicon halides as starting materials chlorine containing
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    • C03C2203/00—Production processes
    • C03C2203/50—After-treatment
    • C03C2203/52—Heat-treatment
    • C03C2203/54—Heat-treatment in a dopant containing atmosphere
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Abstract

The present invention provides a TiO2-SiO2 glass whose coefficient of linear thermal expansion in the range of the time of irradiation with EUV light is substantially zero when used as an optical member of an exposure tool for EUVL and which has extremely high surface smoothness. The present invention relates to a TiO2-containing silica glass having a TiO2 content of from 7.5 to 12 % by mass, a temperature at which a coefficient of linear thermal expansion is 0 ppb/ DEG C, falling within the range of from 40 to 110 DEG C, and a standard deviation (s) of a stress level of striae of 0.03 MPa or lower within an area of 30 mm x 30 mm in at least one plane.

Description

Contain TiO 2Silica glass and the EUV photoetching of using high-energy-density with optics and the special temperature-controlled process that is used for its manufacturing
Technical field
The present invention relates to a kind of TiO of containing 2Silica glass (hereinafter be called in this manual, " TiO 2-SiO 2Glass "), and especially, relate to a kind for the treatment of as the TiO of EUV photoetching with the optics of exposure tool 2-SiO 2Glass.The EUV that relates among the present invention (extreme ultraviolet) refers to that only the light of wavelength at soft X-ray district or vacuum ultraviolet, particularly wavelength are at about light of 0.2 to 100nm.
Background technology
In photoetching technique, extensively utilized so far by minute circuit pattern being transferred on the wafer to make the exposure tool of unicircuit.Be accompanied by the development trend of the highly integrated and multifunction of unicircuit, the microminiaturization of unicircuit advances.Therefore, need exposure tool on wafer surface, to form and have high-resolution circuit pattern image, and the short wavelengthization of exposure light source is pushed ahead with the long depth of focus.Exposure light source is just from the g line of routine (wavelength: 436nm), i line (wavelength: 365nm) and KrF excimer laser (wavelength: 248nm) further advance, and brought into use ArF excimer laser (wavelength: 193nm).And, will become unicircuit of future generation below the 70nm in order to tackle circuit line width, all use the immersion lithography of ArF excimer laser and double exposure techniques to be considered to have leading property separately.Yet now think to have that generation unicircuit that live width is up to 45nm even use these technology also to be merely able to solve.
Under above-mentioned technological trend, use wavelength representative in the EUV light (extreme ultraviolet) to be considered to be applicable to a 32nm and a generation subsequently as the photoetching technique of exposure light source, thereby cause concern as the light of 13nm.From using the viewpoint of projection optical system with the mask pattern transfer printing, it is identical with conventional photoetching that the image of EUV photoetching (hereinafter being called " EUVL ") forms principle.Yet, owing in the energy area of EUV light, can not make the material of light transmission, so can not use dioptric system.Therefore, described optical system all is a reflective optics.
EUVL comprises photomask and mirror with the optics of exposure tool, and is reflecting the absorber layers formation that forms on the multilayer by (1) base material, (2) in the reflection multilayer that forms on the base material and (3) basically.For described reflection multilayer, studied the wherein Mo/Si reflection multilayer of Mo layer and Si layer alternatively laminated; For described absorber layers, Ta and Cr have been studied.For described base material, need have the material of low thermal coefficient of expansion, thereby even also do not produce strain using under the EUV photoirradiation, and studied glass with low thermal coefficient of expansion etc.
Known TiO 2-SiO 2Glass is the utmost point low thermal expansion material that thermal expansivity (CTE) is lower than silica glass.And, because by the TiO in the glass 2Content can be controlled thermal expansivity, approaches 0 zero expansion glass so can obtain thermal expansivity.Therefore, TiO 2-SiO 2Glass might be as the material that uses in the optics of EUVL with exposure tool.
According to TiO 2-SiO 2The conventional preparation method of glass at first, is converted into gas phase, intermingling then separately with silica precursor and titanium dioxide precursor.The mixture that will be in gas phase is introduced in the burner and thermolysis, thereby forms TiO 2-SiO 2Glass particle.With this TiO 2-SiO 2Glass particle deposits in refractory container, and in the fusion therein of sedimentary while, thereby form TiO 2-SiO 2Glass.And patent documentation 1 discloses a kind of method, wherein forms TiO 2-SiO 2Porous vitreum, and be converted into vitreum, obtain mask substrate then.
Yet, by the TiO of these method preparations 2-SiO 2Glass has produced TiO 2/ SiO 2The cyclic fluctuation of ratio of components, and this shows as the striped that spacing is the bar shaped of 10 to 200 μ m.Using TiO 2-SiO 2Glass, must become to make its surface have high surface smoothness with under the situation of optics as the EUV photoetching with described glass polishing.Yet, at TiO 2-SiO 2In the glass, because TiO 2/ SiO 2The position that ratio of components is different depends on described ratio of components, and makes the machinery of glass also different with chemical property, so that polishing speed becomes is unfixing.Therefore, be difficult to after polishing, finish grind (finish) glass surface to make it having high surface smoothness.When to having the TiO that spacing is the bar shaped striped of 10 to 200 μ m 2-SiO 2During glass polishing, produce " ripple " with spacing identical with the fringe spacing grade.Therefore, be difficult to obtain high surface smoothness.
In order to obtain high surface smoothness, preferably at TiO 2/ SiO 2The TiO that has minor swing in the ratio of components 2-SiO 2Glass.In patent documentation 2, the inventor is to obtaining porous TiO 2-SiO 2The speed of rotation of seed rod and transparent TiO in the Vitrea stage 2-SiO 2Relation between the Vitrea striped has been carried out extensive and deep research, found that the speed of rotation of seed rod is high more, and striped is more little, and transparent TiO 2-SiO 2Vitrea TiO 2The variation of concentration is more little.And they disclose in the zone of the 30mm * 30mm at least one face, and the fluctuating range of specific refractory power (Δ n) is 2 * 10 -4Following TiO 2-SiO 2Glass.
Patent documentation 3 discloses the silica glass that contains titanium dioxide with low-level striped and the optics that is used for vacuum-ultraviolet light, with and manufacture method.
In patent documentation 4, the width that the contriver discloses fictive temperature and zero thermal expansion temperature range is to be mutually related, and promptly described fictive temperature and Δ T are interrelated, and more particularly, when fictive temperature was high, Δ T was narrow; And when fictive temperature was low, Δ T was wide.
Patent documentation 1:US-A-2002-157421
Patent documentation 2:JP-A-2004-315351
Patent documentation 3:JP-T-2005-519349
Patent documentation 4:JP-A-2005-104820
Summary of the invention
In order to improve the flux of EUVL with exposure tool, the energy that increases the EUV light that is ready to use in exposure is effective.Therefore, thus have the temperature of parts raise to surpass to estimate the possibility of temperature in this case.Specifically, because temperature might be increased to 40 to 110 ℃ temperature range, so preferably, expanding under said temperature is zero substantially.This is in order to prevent the change of pattern-pitch under the situation of photomask etc.; With the change that under the situation of stepping mirror (stepper mirror) etc., prevents shape.
Known TiO 2-SiO 2The thermal linear expansion coefficient of glass is with contained TiO 2Concentration and change (for example, seeing P.C.Schultz and H.T.Smyth, in:R.W.Douglas and B.Ellis, Amorphous Materials (amorphous material), Willey, New York, p.453 (1972)).
Therefore, can be by regulating TiO 2-SiO 2The TiO of glass 2Content is regulated the temperature when realizing zero thermal expansion.Specifically, at 22 ℃ of conventional TiO that realize zero thermal expansion down 2-SiO 2In the glass, TiO 2Concentration be about 7 quality %.Yet, improving the TiO that uses under the situation of EUVL with the flux of exposure tool 2-SiO 2In the glass, owing to under the temperature more than 40 ℃, realize zero thermal expansion, so TiO 2Concentration must therefore must improve TiO more than near the 7.5 quality % 2Concentration.
In order to improve TiO 2-SiO 2The TiO of glass 2Concentration must improve as TiO 2-SiO 2The relative quantity of the titanium dioxide precursor of frit.Compare with silica precursor, described titanium dioxide precursor has high boiling point usually, and after being converted into the steam attitude, is easy to cause dewfall in being transported to the way of burner.For this reason, above-mentioned routine techniques causes following problem: when the relative quantity of titanium dioxide precursor was high, dewfall took place during transporting, thus the TiO in the final glass that obtains 2/ SiO 2Ratio of components produces fluctuation.And, even when dewfall not taking place, because TiO 2The increase of concentration, TiO 2/ SiO 2It is big that the fluctuating range of ratio of components also becomes.And, because TiO 2/ SiO 2The position that ratio of components is different depends on described ratio of components, and the machinery of glass is different with chemical property, so that polishing speed becomes is unfixing.Thus, generation can not obtain to have the problem of the glass of very high surface smoothness.
In order to solve the problems referred to above of routine techniques, the purpose of this invention is to provide a kind of TiO that is intended to increase flux 2-SiO 2Glass, as the exposure tool optics of the light that uses high EUV energy, it has suitable hot expansibility, and can give high surface smoothness.More particularly, the purpose of this invention is to provide a kind of TiO 2-SiO 2Glass, when its as EUVL with optics of exposure tool, scope with the photoirradiation of high EUV energy the time in, its thermal linear expansion coefficient is zero substantially, and has high surface smoothness.
The invention provides a kind of TiO of containing 2Silica glass, the TiO of described silica glass 2Content is 7.5 to 12 quality %, and the temperature when thermal linear expansion coefficient is 0ppb/ ℃ is in 40 to 110 ℃ the scope, and is below the 0.03MPa in the zone of the 30mm * 30mm of the standard deviation of fringe stress level (σ) at least one face.
The invention provides a kind of TiO of containing 2Silica glass, the TiO of described silica glass 2Content is 7.5 to 12 quality %, and the temperature when thermal linear expansion coefficient is 0ppb/ ℃ is in 40 to 110 ℃ the scope, and is below the 0.2MPa in the zone of the 30mm * 30mm of the maximal roughness of fringe stress level (PV) at least one face.
And, the invention provides a kind of TiO of containing 2Silica glass, the TiO of described silica glass 2Content is 7.5 to 12 quality %, and the temperature when thermal linear expansion coefficient is 0ppb/ ℃ is in 40 to 110 ℃ the scope, and is 4 * 10 in the zone of the 30mm * 30mm of the fluctuating range of specific refractory power (Δ n) at least one face -4Below.
Preferably, TiO of the present invention 2-SiO 2The average thermal linear expansion coefficient of glass in 20 to 100 ℃ of scopes is below 60ppb/ ℃.
Preferably, TiO of the present invention 2-SiO 2The fictive temperature of glass is below 1100 ℃.
Preferably, TiO of the present invention 2-SiO 2Glass does not contain inclusion.
And, TiO of the present invention 2-SiO 2Glass can be used as EUV photoetching optics, and uses TiO of the present invention 2-SiO 2The EUV photoetching of glass is preferably below the 3nm with the surface smoothness (rms) of optics.
The invention provides a kind of above-mentioned TiO of containing 2The manufacture method of silica glass, comprising:
With the silica precursor gasification,
With the titanium dioxide precursor gasification, and
Transport the silica precursor of gasification and the titanium dioxide precursor of gasification respectively by pipe A and pipe B, thereby to the precursor of burner supply gasification,
Wherein said pipe B is configured to have towards the direction of described burner the temperature of rising.
At the above-mentioned TiO that contains of the present invention 2The manufacture method of silica glass in, preferably, control described pipe B by PID, thus make its in the temperature fluctuation amplitude of each point in ± 1 ℃.
At the above-mentioned TiO that contains of the present invention 2The manufacture method of silica glass in, preferably, the volumometer when being scaled normal atmosphere, the gas flow rate among the described pipe B is more than 0.1 meter per second.
At the above-mentioned TiO that contains of the present invention 2The manufacture method of silica glass in, preferably, this method further is included in the step that is supplied to before the burner each gas stirring.
At the above-mentioned TiO that contains of the present invention 2The manufacture method of silica glass in, preferably, this method further comprises the TiO that is shaped with the regulation shape 2-SiO 2Glass shaping body kept under 600 to 1200 ℃ temperature more than 2 hours, then with the average rate of temperature fall below 10 ℃/hour temperature was reduced to step below 500 ℃.
TiO of the present invention 2-SiO 2Glass rises with respect to temperature with the photoirradiation of high EUV energy the time, and the change of its size and dimension during than room temperature is very little, and obtains surface with very high surface smoothness, so it is suitable as the optics of EUVL with exposure tool very much.
Description of drawings
Fig. 1 is the figure that draws the relation between CTE and the temperature.
Embodiment
In the present invention, TiO 2Content be 7.5 to 12 quality %.If TiO 2Content in above-mentioned scope, the temperature when thermal linear expansion coefficient (CTE) is 0ppb/ ℃ so (is crossed over temperature; COT) tend to be in 40 to 110 ℃ the scope.Specifically, work as TiO 2Content during less than 7.5 quality %, described COT tends to be lower than 40 ℃.And, work as TiO 2Content when surpassing 12 quality %, described COT tends to surpass 110 ℃, perhaps tends to take place negative expansion in-150 to 200 ℃ scope.And, have the crystal of rutile etc. to be easy to separate out, or bubble is easy to residual possibility.TiO 2Content be preferably below the 11 quality %, more preferably below the 10 quality %.And, TiO 2Content be preferably more than the 8 quality %, more preferably more than the 8.5 quality %.
When carrying out EUVL, cause the change of size and dimension in order to prevent temperature change because of optics such as mirror, in the present invention preferably, described COT is in 40 to 110 ℃ the scope, is preferably 45 to 100 ℃, is preferably 50 to 80 ℃ especially.
In the present invention, be below the 0.03MPa in the zone of the 30mm * 30mm of the standard deviation of fringe stress level (σ) at least one face.When described standard deviation (σ) surpasses 0.03MPa, there is the surfaceness after the polishing to become big, thereby can not get the possibility of high surface smoothness.Described standard deviation (σ) more preferably below the 0.02MPa, is preferably below the 0.01MPa especially.
In the present invention, be preferably below the 0.2MPa in the zone of the 30mm * 30mm of the maximal roughness of fringe stress level (PV) at least one face.When described maximal roughness (PV) surpasses 0.2MPa, because TiO 2/ SiO 2The position that ratio of components is different depends on described ratio of components, and the machinery of glass is also different with chemical property, so that polishing speed becomes is unfixing.For this reason, there is the surfaceness after the polishing to become big, thereby can not get the possibility of very high surface smoothness.Described maximal roughness (PV) more preferably below the 0.17MPa, below the further preferred 0.15MPa, is preferably below the 0.10MPa especially.
In the present invention, be preferably below the 0.2MPa in the zone of the 30mm * 30mm of the rootmean-square of fringe stress level (RMS) at least one face.When described rootmean-square (RMS) is 0.2MPa when following, there is the surfaceness after the polishing to diminish, thereby can be easy to obtain the possibility of high surface smoothness.Described rootmean-square (RMS) more preferably below the 0.17MPa, more preferably below the 0.15MPa, is preferably below the 0.1MPa especially.
TiO 2-SiO 2The fringe stress of glass can be by for example being determined with definite its delay and according to following formula by the about 1mm of use double refraction measurement microscope * 1mm zone by currently known methods.
Δ＝C×F×n×d
Here, Δ is represented to postpone; C represents photoelastic constant; F represents stress; N represents specific refractory power; D represents thickness of sample.
Determine the distribution (profile) of stress, the deviation that therefrom can settle the standard (σ), maximal roughness (PV) and rootmean-square (RMS) by aforesaid method.More particularly, for example, from transparent TiO 2-SiO 2Cut out the cubes of about 40mm * 40mm * 40mm in the vitreum, cut into slices from cubical each face, polish then to obtain the tabular TiO of 30mm * 30mm * 0.5mm with the thickness of about 1mm 2-SiO 2Glass block.Use the double refraction microscope, vertically apply He-Ne Lasers on the 30mm * 30mm face to this glass block, amplify with the multiple that can fully observe striped then; Delay in the check surface distributes, and it is scaled stress distribution.Under the very thin situation of the spacing of striped, must make tabular TiO to be determined 2-SiO 2The thickness of glass block is thin.
In the present invention, be preferably 4 * 10 in the zone of the 30mm * 30mm of the fluctuating range of specific refractory power (Δ n) at least one face -4Below.When the fluctuating range (Δ n) of described specific refractory power surpasses 4 * 10 -4The time, there is the surfaceness after the polishing to become big, thereby can not get the possibility of high surface smoothness.The fluctuating range of described specific refractory power (Δ n) more preferably 3.5 * 10 -4Below, more preferably 3 * 10 -4Below.
Especially, in order to obtain high surface smoothness such as surface smoothness (rms)≤1nm, the fluctuating range of described specific refractory power (Δ n) is preferably 2 * 10 -4Below, more preferably 1.5 * 10 -4Below, more preferably 1 * 10 -4Below, be preferably 0.5 * 10 especially -4Below.
Measuring method about the fluctuating range Δ n of specific refractory power can pass through currently known methods, for example by using optical interdferometer to carry out.More particularly, for example, from transparent TiO 2-SiO 2Cut out the cubes of about 40mm * 40mm * 40mm in the vitreum, cut into slices from cubical each face, polish then to obtain the tabular TiO of 30mm * 30mm * 0.2mm with the thickness of about 0.5mm 2-SiO 2Glass block.Use small-bore fizeau interferometer, the light that only has specific wavelength that uses wave filter to take out from white light vertically is applied on the face of 30mm * 30mm of this glass block, amplify with the magnification that can fully observe striped then; Delay in the check surface distributes, thereby measures the fluctuating range Δ n of specific refractory power.Under the very thin situation of the spacing of striped, must make tabular TiO to be determined 2-SiO 2The thickness of glass block is thin.
State double refraction microscope or optical interdferometer in the use and estimate under the situation of striped, the size of a pixel may be inadequately little than the width of striped among the CCD, thereby may not fully detect striped.In this case, preferably, the whole zone in 30mm * 30mm is divided into for example a plurality of tiny areas of about 1mm * 1mm, thereby carries out the mensuration of each tiny area.
At TiO of the present invention 2-SiO 2In the glass, TiO in the zone of the 30mm * 30mm in a face 2The maximum value of concentration and the difference of minimum value are preferably below the 0.06 quality %, more preferably below the 0.04 quality %.When this difference is 0.06 quality % when following, there is the surfaceness after the polishing to diminish, thereby can be easy to obtain the possibility of high surface smoothness.
As being used to make TiO of the present invention 2-SiO 2The method of glass has following several method.Manufacture method as an one example is: will carry out flame hydrolysis or thermolysis, the TiO that obtains as the silica precursor and the titanium dioxide precursor of glass formation raw material separately 2-SiO 2Granulated glass (soot) deposits by the soot method and grows, thereby obtains porous TiO 2-SiO 2Vitreum; Then, under decompression or helium-atmosphere, with the porous TiO that obtains 2-SiO 2Vitreum is heated to more than the densification temperature, and further is heated to more than the transparent glass temperature, thereby obtains TiO 2-SiO 2Vitreum.Depend on preparation method, the example of described soot method comprises MCVD method, OVD method and VAD method.
Also there is following manufacture method: will form silica precursor and titanium dioxide precursor in 1800 to 2000 ℃ of following hydrolysis and oxidations in oxyhydrogen flame of raw material separately as glass, thereby obtain TiO 2-SiO 2Vitreum.
The densification temperature of mentioning in this specification sheets is meant the temperature when porous vitreum is densified to can not confirm the space by opticmicroscope.And, the temperature when the transparent glass temperature of mentioning herein is meant and can not confirms crystal and obtain transparent glass by opticmicroscope.
At this moment, in order to obtain TiO 2-SiO 2Glass, the relative quantity that must increase the titanium dioxide precursor that is used as raw material is to increase TiO 2Concentration.Compare with silica precursor, described titanium dioxide precursor has high boiling point usually, and after being converted into the steam attitude, is easy to cause dewfall in being transported to the way of burner.And, because TiO 2The increase of concentration makes TiO 2/ SiO 2It is big that the fluctuating range of ratio of components becomes.
In order to obtain the TiO that the present invention has little striped 2-SiO 2Glass must be controlled fully and is used to transport the pipe of raw material, particularly transports the temperature of the pipe of titanium dioxide precursor.The inventor finds, under the situation of the titanium dioxide precursor gasification that makes high density by bubbling, in order to reduce striped, it is effective controlling that described Guan Wen is higher than the bubbling temperature and sets for along with the temperature of advancing towards the burner direction raises.When there being the low-temp. portion timesharing, temporarily reducing at low temperature part gas volume, thereby make the concentration of the titanium dioxide precursor of waiting to introduce burner become inhomogeneous.
And the inventor finds that the fluctuation of Guan Wen causes striped.For example, when transporting TiCl with 0.5 meter per second 4Pipe in, in the part of the pipe of long 2m gas temperature with cycle of 30 seconds during with 130 ℃ ± 1.5 ℃ fluctuations, the composition fluctuation that produces 0.1 weight %.For this reason, in order to obtain TiO of the present invention 2-SiO 2Glass, preferably by PID control, control transport titanium dioxide precursor pipe temperature to the temperature fluctuation amplitude in ± 1 ℃.Described temperature fluctuation amplitude is more preferably in ± 0.5 ℃.And, except the pipe that transports titanium dioxide precursor, preferably by PID control, control transport silica precursor pipe temperature to the temperature fluctuation amplitude in ± 1 ℃.Described temperature fluctuation amplitude is more preferably in ± 0.5 ℃.In order to heat described pipe, for heating described pipe this purpose equably, it is preferred centering on described pipe coiling flexible heater such as band heater or rubber heater.In order to heat described pipe more equably, preferably use aluminium foil to cover described pipe and well heater.In addition preferably, use thermal insulation material such as carbamate or heat resistance fiber cloth to cover the most surperficial layer.In addition, form fluctuation, can improve the gas flow rate in the described pipe in order to reduce.Volumometer when being scaled normal atmosphere, described flow velocity is preferably more than 0.1 meter per second, more preferably more than 0.3 meter per second, more preferably more than 0.5 meter per second, is preferably especially more than 1 meter per second.
For supply gas equably, preferably in burner, before supply silica precursor and the titanium dioxide precursor gas stirring mechanism is being set.As stirring mechanism, can regard them as two kinds: a kind of mechanism segments gas by parts such as static mixer or strainer, then gas is collaborated; Thereby a kind of mechanism produces average fine fluctuation, supply gas thus by gas is introduced in the big space.In order to obtain TiO of the present invention 2-SiO 2Glass, preferably by using at least a above-mentioned stirring mechanism to prepare described glass, more preferably two kinds are all used.And in described stirring mechanism, preferably static mixer and strainer all use.
At TiO of the present invention 2-SiO 2In the glass, preferably, the average thermal linear expansion coefficient in 20 to 100 ℃ of scopes is below 60ppb/ ℃.Thus, when using high-energy EUV light to carry out irradiation, even when the temperature of optics when room temperature rises to high temperature, also can be reduced in size and the change of shape.Average thermal linear expansion coefficient in 20 to 100 ℃ of scopes more preferably below 50ppb/ ℃, more preferably below 40ppb/ ℃, is preferably below 30ppb/ ℃ especially.On the other hand, at COT is under the pyritous situation, although it is negative value that the average thermal linear expansion coefficient in 20 to 100 ℃ of scopes tends to, because same reason, preferably the absolute value of the average thermal linear expansion coefficient in 20 to 100 ℃ of scopes is little.Average thermal linear expansion coefficient in 20 to 100 ℃ of scopes is preferably-more than the 120ppb/ ℃, more preferably-more than the 100ppb/ ℃, more preferably-more than the 60ppb/ ℃.When using high-energy EUV light to carry out irradiation, want to make under the littler situation of the change of size or shape, average thermal linear expansion coefficient in 20 to 100 ℃ of scopes is preferably-more than the 50ppb/ ℃, more preferably-more than the 40ppb/ ℃, and be preferably especially-more than the 30ppb/ ℃.
And preferably, at TiO of the present invention 2-SiO 2In the glass, the temperature amplitude when thermal linear expansion coefficient (CTE) is 0 ± 5ppb/ ℃ (Δ T) is more than 5 ℃.Under Δ T is situation more than 5 ℃, when using described TiO 2-SiO 2When glass is used the optics of exposure tool as EUVL, when using the EUV photoirradiation, suppressed the thermal expansion of described optics.Δ T is more preferably more than 6 ℃, more preferably more than 8 ℃.Δ T is to be particularly preferred more than 15 ℃, because CTE can reach 0 ± 5ppb/ ℃ in 50 to 80 ℃ temperature range.
At TiO of the present invention 2-SiO 2In the glass, TiO preferably 2Content be 7.5 to 12 quality %, and fictive temperature is below 1100 ℃.When fictive temperature is below 1100 ℃ the time, the average thermal linear expansion coefficient in 20 to 100 ℃ of scopes tends to become below 60ppb/ ℃; And using described TiO 2-SiO 2Glass is as under the situation of EUVL with the optics of exposure tool, when using the EUV photoirradiation, suppressed the thermal expansion that the temperature change owing to optics causes.
Described fictive temperature is more preferably below 1000 ℃, and more preferably below 950 ℃.In order to be reduced in 20 to 100 ℃ of average thermal linear expansion coefficients in the scope more, described fictive temperature is preferably below 900 ℃, more preferably below 850 ℃, is preferably especially below 800 ℃.
By currently known methods, for example by in-150 to+200 ℃ of temperature ranges, using laser interference dilatometer measurement TiO 2-SiO 2The thermal linear expansion coefficient of glass (CTE), and, can determine described TiO as shown in fig. 1 to the mapping of the relation between CTE and temperature 2-SiO 2The COT of glass, average thermal linear expansion coefficient and Δ T in 20 to 100 ℃ of scopes.
In order to obtain fictive temperature is TiO of the present invention below 1100 ℃ 2-SiO 2Glass, following method are effective: will be with the TiO of regulation shape shaping 2-SiO 2Glass shaping body keeps being cooled to below 500 ℃ with the average rate of temperature fall below 10 ℃/hour then more than 2 hours under 600 to 1200 ℃ temperature.In order further to reduce fictive temperature again, preferably with the speed below 5 ℃/hour, more preferably lower the temperature with the speed below 3 ℃/hour.When lowering the temperature, obtain lower fictive temperature with slower average rate of temperature fall.For example, when lowering the temperature with the speed below 1 ℃/hour, fictive temperature can be for below 900 ℃.But in this case, when only in 1000 to 800 ℃ temperature range with low rate of cooling, as lowering the temperature with the speed below 1 ℃/hour, and when in other temperature province, cooling off, can shorten the time with the rate of cooling more than 5 ℃/hour.
Can measure TiO by known procedure 2-SiO 2The fictive temperature of glass.In the following embodiments, measure TiO by following operation 2-SiO 2The fictive temperature of glass.
To bright finished TiO 2-SiO 2Glass obtains absorption spectrum by infrared spectrometer (Magna 760, and Buddhist nun's high-tensile strength company makes, and uses) in following embodiment.In this mensuration, data gathering is set at about 0.5cm at interval -1, and will be used for absorption spectrum by the mean value that scans 64 acquisitions.In the infrared absorption spectrum that obtains like this, at about 2260cm -1Near observed peak is owing to TiO 2-SiO 2The overtone of the stretching vibration of the Si-O-Si key of glass.By using this peak position, make working curve by the glass of same composition, thereby determine fictive temperature with known fictive temperature.Perhaps, by using identical infrared spectrometer, measure the reflection spectrum on surface in an identical manner.In the Infrared Reflective Spectra that obtains like this, at about 1120cm -1Near observed peak is owing to TiO 2-SiO 2The stretching vibration of the Si-O-Si key of glass.By using this peak position, make working curve by the glass of same composition, thereby determine fictive temperature with known fictive temperature.Moving of the peak position that can cause from the variation that the composition and the dependency extrapolation of working curve are made up of glass.
When using TiO of the present invention 2-SiO 2When glass was used the optics of exposure tool as EUVL, the viewpoint of the variation of the thermal linear expansion coefficient from reduce glass importantly made the TiO in the glass 2/ SiO 2Ratio of components even.
At TiO of the present invention 2-SiO 2In the glass, the variation of fictive temperature is preferably in 50 ℃, more preferably in 30 ℃.When the variation of fictive temperature surpasses above-mentioned scope, worry to depend on the difference of position, between thermal linear expansion coefficient, produce difference.
In this manual, " variation of fictive temperature " is defined in the zone of the 30mm * 30mm at least one face, the maximum value of fictive temperature and minimum value poor.
Variation that can following mensuration fictive temperature.The transparent TiO that will be shaped with specified dimension 2-SiO 2The vitreum section is to form the TiO of 50mm * 50mm * 1mm 2-SiO 2Glass block.To this TiO 2-SiO 2The 50mm of glass block * 50mm face by measuring the fictive temperature every the 10mm spacing according to aforesaid method, thereby measures the TiO that is shaped 2-SiO 2The variation of Vitrea fictive temperature.
In order to make TiO of the present invention 2-SiO 2Glass can adopt to may further comprise the steps (a) manufacture method to (e).
Step (a):
Will be by forming the TiO that the flame hydrolysis of the silica precursor of raw material and titanium dioxide precursor obtains as glass separately 2-SiO 2Granulated glass deposits on base material and grows, thereby forms porous TiO 2-SiO 2Vitreum.Described glass forms raw material and is not particularly limited, so long as can get final product by vaporized raw material.The example of described silica precursor comprises silicon halogenide, for example muriate such as SiCl 4, SiHCl 3, SiH 2Cl 2, SiH 3Cl; Fluorochemical such as SiF 4, SiHF 3, SiH 2F 2Bromide such as SiBr 4, SiHBr 3With iodide such as SiI 4And R nSi (OR) 4-nThe organoalkoxysilane (wherein R represents that carbonatoms is 1 to 4 alkyl, and n represents 0 to 3 integer, and described a plurality of R can be identical or different) of expression.And the example of described titanium dioxide precursor comprises titanium halide such as TiCl 4, TiBr 4, and R nTi (OR) 4-nThe titan-alkoxide (wherein R represents that carbonatoms is 1 to 4 alkyl, and n represents 0 to 3 integer, and described a plurality of R can be identical or different) of expression.And, the compound that can use Si and Ti as the two alkoxide of silicon titanium as described in silica precursor and as described in titanium dioxide precursor.
Can use the seed rod of making by silica glass (seed rod of for example, in JP-B-63-24973, describing) as base material.And the shape of base material to be used is not limited to shaft-like, also can be tabular.
When supply glass forms raw material, preferably come the supply of stabilized glass unstripped gas by the gentle gas velocity of control aforementioned tube.
And, preferably, in the gas supply system, be provided with the above-mentioned stirring mechanism of glass raw material gas.
According to they each, can reduce described TiO 2-SiO 2The striped level of glass, and the stress level of striped and the fluctuating range of specific refractory power all can be controlled at below the prescribed value.
As mentioned above, the inventor is to obtaining porous TiO 2-SiO 2The speed of rotation of seed rod and transparent TiO in the Vitrea stage 2-SiO 2Relation between the Vitrea striped has been carried out extensive and deep research, and they find as a result, and the speed of rotation of seed rod is high more, and striped is more little, and transparent TiO 2-SiO 2Vitrea TiO 2The variation of concentration more little (seeing patent documentation 2).
In the present invention, except the aforementioned stableization when supplying raw material, preferably, forming porous TiO 2-SiO 2During vitreum, with the above rotary seed crystal rod of 25rpm.More preferably with more than the 50rpm, further preferably with more than the 100rpm, especially preferably to be rotated more than the 250rpm.
Except stabilization or homogenizing when supplying raw material,, also obtained to have the TiO of little striped by with the high speed rotating seed rod with the steam attitude 2-SiO 2Glass.
Step (b):
Under decompression or helium-atmosphere, the porous TiO that will in step (a), obtain 2-SiO 2Vitreum is warming up to densification temperature, thereby obtains TiO 2-SiO 2DB.Described densification temperature is generally 1250 to 1550 ℃, is preferably 1300 to 1500 ℃ especially.
Step (c):
The TiO that will in step (b), obtain 2-SiO 2DB is warming up to the transparent glass temperature, thereby obtains transparent TiO 2-SiO 2Vitreum.Described transparent glass temperature is generally 1350 to 1800 ℃, is preferably 1400 to 1750 ℃ especially.
The atmosphere of preferred 100% rare gas element such as helium or argon, perhaps contain rare gas element such as helium or argon as the atmosphere of principal constituent as atmosphere.Pressure can be decompression or normal pressure.Under the situation of decompression, pressure is preferably below the 13000Pa.
Step (d):
The transparent TiO that will in step (c), obtain 2-SiO 2Vitreum heats under the temperature more than the softening temperature, and is configured as desired shape, thereby obtains the TiO of shaping 2-SiO 2Vitreum.Forming temperature is preferably 1500 to 1800 ℃.When the shaping temperature is lower than 1500 ℃, because transparent TiO 2-SiO 2The viscosity height of glass is not so carry out the deformation that caused by deadweight substantially.And, tend to take place as SiO 2The growth of the cristobalite of crystallization phases, or as TiO 2The rutile of crystallization phases or the growth of anatase octahedrite, thus so-called devitrification caused.When the shaping temperature surpassed 1800 ℃, existence can't be ignored SiO 2The possibility of distillation.
Can be continuously or carry out step (c) and step (d) simultaneously.
Step (e):
The TiO of the shaping that will in step (d), obtain 2-SiO 2Vitreum kept under 600 to 1200 ℃ temperature more than one hour, carried out anneal being cooled to below 500 ℃ with the average rate of temperature fall below 10 ℃/hour then, thus control TiO 2-SiO 2The fictive temperature of glass.Perhaps, with the average rate of temperature fall below 60 ℃/hour, to shaping TiO in the acquisition in step (d) more than 1200 ℃ 2-SiO 2Vitreum carries out anneal being cooled to below 500 ℃, thus control TiO 2-SiO 2The fictive temperature of glass.After being cooled to below 500 ℃, can adopt naturally cooling.In this case, the atmosphere of preferred 100% rare gas element of atmosphere such as helium, argon or nitrogen contains the atmosphere of this class rare gas element as principal constituent, or air atmosphere; Pressure preferably reduces pressure or normal pressure.
In order to obtain lower fictive temperature, it is effective cooling off with slower rate of cooling near the temperature province ANNEALING OF GLASS point or strain point.And, cause the irregular striped of glazed surface, be not only by because of TiO 2/ SiO 2The fluctuation of ratio of components and stress that the glass machinery that causes and the difference in the chemical property produce causes, and caused by the stress because of the difference generation of forming the thermal linear expansion coefficient that difference causes.Therefore, in order to reduce interfringe stress to suppress the polishing irregular formation in back, near the temperature province ANNEALING OF GLASS point or strain point, it is effective cooling off with slower rate of cooling.Specifically, rate of cooling is preferably below 10 ℃/hour the most slowly in the cooling of step (e) distributes, and more preferably below 5 ℃/hour, more preferably below 3 ℃/hour, is preferably especially below 1 ℃/hour.
Especially, in order to obtain lower fictive temperature, near the temperature range glass annealing point (for example, annealing point ± 25 ℃), it is effective cooling off with slower rate of cooling.And, in order to reduce interfringe stress suppressing the polishing irregular formation in back, near the temperature province strain point of glass (for example, strain point ± 25 ℃) to cool off with slower rate of cooling be effective.
Preferably, TiO of the present invention 2-SiO 2Glass does not contain inclusion.The inclusion of mentioning herein is meant the foreign matter that exists in the glass, bubble etc.In glass manufacturing process, exist because of polluting or crystal is separated out the worry that produces foreign matter.In order to eliminate described inclusion such as foreign matter or bubble, must in step (a), control pollution especially, and the temperature condition of further accurate controlled step (b) to (d).
Use TiO of the present invention 2-SiO 2The EUVL of glass is easy to obtain to have the surface of very high surface smoothness with the optics of exposure tool.
Use TiO of the present invention 2-SiO 2The EUVL of glass is preferably below the 3nm with the surface smoothness (rms) of the optics of exposure tool, more preferably below the 2nm, more preferably below the 1.5nm, is preferably below the 1nm especially.
Measure the surface smoothness (rms) on described surface by the following method.
To bright finished glass surface, measure the surface shape for the treatment of as in the zone of optics by noncontact surface shape measuring system (New View5032, Zhai Ke (Zygo) company makes).This is measured, use object lens with 2.5 magnifications.The surface shape of measuring is cut apart by per 2 * 2mm square region, calculated the rms value from these zones then, be defined as smoothness with this.And, when calculating the rms value, use bandpass filter to carry out data processing, and eliminate ripple composition with the wavelength except that above-mentioned wavelength region may with 10 μ m to 1mm wavelength.
Embodiment
To illustrate in greater detail the present invention with reference to following examples, not explain but the present invention should not be limited to these embodiment.Embodiment 1 to 5 is examples, and remaining is comparative example.
Embodiment 1
By will be separately as TiO 2-SiO 2The glass of glass forms the TiCl of raw material 4And SiCl 4Gasify respectively, then they are mixed, and in oxyhydrogen flame, mixture is carried out heating hydrolysis (flame hydrolysis) and can obtain TiO 2-SiO 2Granulated glass, the deposition and the described TiO that grows on the seed rod that rotates with the speed of rotation of 250rpm 2-SiO 2Granulated glass, thus porous TiO formed 2-SiO 2Vitreum (step (a)).
Control SiCl by PID 4And TiCl 4Pipe separately, thus the fluctuating range that makes the gas temperature in the pipe is in ± 0.5 ℃.Gas flow rate in the pipe is 3.04 meter per seconds.Control described pipe, thereby make its temperature be configured to be higher than the bubbling temperature, and be arranged to have the temperature of rising towards the burner direction.In burner, supplying SiCl 4And TiCl 4Before each, the stirring mechanism of unstripped gas is set.
Owing to do not carry out the porous TiO that any processing then is difficult to operate acquisition 2-SiO 2So vitreum is with the porous TiO that obtains 2-SiO 2Vitreum kept 6 hours down in 1200 ℃ in air with base material, separated from base material then.
Afterwards, with porous TiO 2-SiO 2Vitreum places the controlled electric furnace of atmosphere, and at room temperature pressure is reduced to 1300Pa.Afterwards, in helium atmosphere temperature is risen to 1450 ℃, described then system kept 4 hours under this temperature, thereby obtained TiO 2-SiO 2DB (step (b)).
In argon atmospher, use the carbon stove with the TiO that obtains 2-SiO 2DB is heated to 1700 ℃, thereby obtains transparent TiO 2-SiO 2Vitreum (step (c)).
With the transparent TiO that obtains 2-SiO 2Vitreum is heated to 1750 ℃, and is configured as desired shape, thereby obtains shaping TiO 2-SiO 2Vitreum (step (d)).
The glass that obtains was kept 10 hours down at 1100 ℃, be cooled to 500 ℃ with 3 ℃/hour speed then, then make it leave standstill naturally cooling (step (e)).
Embodiment 2
Except increasing TiCl in embodiment 1 step (a) 4Supply and the speed of rotation of seed rod become outside the 25rpm, use with embodiment 1 in identical mode obtain TiO 2-SiO 2Vitreum.
Embodiment 3
Except increasing TiCl in embodiment 1 step (a) 4Supply, the speed of rotation of seed rod is become 25rpm, and in burner, is supplying SiCl 4And TiCl 4Be not provided with outside the unstripped gas stirring mechanism before each, use with embodiment 1 in identical mode obtain TiO 2-SiO 2Vitreum.
Embodiment 4
Except increasing TiCl in embodiment 1 step (a) a little 4Supply and cool off with the rate of cooling in 10 ℃/hour the speed alternative steps (e) outside, use with embodiment 1 in identical mode obtain TiO 2-SiO 2Vitreum.
Embodiment 5
By will be separately as TiO 2-SiO 2The glass of glass forms the TiCl of raw material 4And SiCl 4Gasify respectively, then they are mixed, and in oxyhydrogen flame, mixture is carried out heating hydrolysis (flame hydrolysis) and can obtain TiO 2-SiO 2Granulated glass, the deposition and the described TiO that grows on the seed rod that rotates with the speed of rotation of 25rpm 2-SiO 2Granulated glass, thus porous TiO formed 2-SiO 2Vitreum (step (a)).Control SiCl by PID 4And TiCl 4Pipe separately, thus the fluctuating range that makes the gas temperature in the pipe is in ± 0.5 ℃.Control described pipe, thereby make its temperature be configured to be higher than the bubbling temperature, and be arranged to have the temperature of rising towards the burner direction.
Owing to do not carry out the porous TiO that any processing then is difficult to operate acquisition 2-SiO 2So vitreum is with the porous TiO that obtains 2-SiO 2Vitreum kept 6 hours down in 1200 ℃ in air with base material, separated from base material then.
Afterwards, with porous TiO 2-SiO 2Vitreum places the controlled electric furnace of atmosphere, and at room temperature pressure is reduced to 1300Pa.Afterwards, in the bubbler of glass, adorn water; Under barometric point, carry out bubbling with He gas in 100 ℃; When introducing water vapour and He gas, described mixture keeping 4 hours under 1000 ℃ and normal pressure under this atmosphere, is mixed thereby carry out OH.
Afterwards, in identical atmosphere, temperature is risen to 1450 ℃, then described mixture was kept 4 hours under this temperature, thereby acquisition contains the TiO of OH 2-SiO 2DB (step (b)).
In argon atmospher, the TiO that contains OH that uses the carbon stove to obtain 2-SiO 2DB is heated to 1700 ℃, thereby obtains to contain the transparent TiO of OH 2-SiO 2Vitreum (step (c)).
With the transparent TiO that contains OH that obtains 2-SiO 2Vitreum is heated to the above temperature (1750 ℃) of softening temperature, and is configured as desired shape, thereby obtains to contain the shaping TiO of OH 2-SiO 2Vitreum (step (d)).
The glass that obtains was kept 10 hours down at 1100 ℃, be cooled to 900 ℃ with 10 ℃/hour speed successively then, be cooled to 700 ℃ with 1 ℃/hour speed, and be cooled to 500 ℃, then make it leave standstill naturally cooling (step (e)) with 10 ℃/hour speed.
Embodiment 6
Except reducing TiCl in embodiment 4 steps (a) 4Supply, the speed of rotation of seed rod is become 25rpm, carries out control, the SiCl of heater temperature by ON-OFF control rather than PID control 4And TiCl 4The fluctuating range of the gas temperature in the pipe is more than ± 2 ℃ and is supplying SiCl in burner separately 4And TiCl 4Be not provided with outside the unstripped gas stirring mechanism before each, use with embodiment 4 in identical mode obtain TiO 2-SiO 2Vitreum.
Embodiment 7
Except reducing TiCl in embodiment 4 steps (a) 4Supply, the speed of rotation of seed rod is become 25rpm, carries out the control and the SiCl of heater temperature by ON-OFF control rather than PID control 4And TiCl 4Separately the fluctuating range of the gas temperature in the pipe be more than ± 2 ℃ outside, use with embodiment 4 in identical mode obtain TiO 2-SiO 2Vitreum.
Embodiment 8
Except reducing TiCl in embodiment 4 steps (a) a little 4Supply, the speed of rotation of seed rod is become 25rpm, in the part of pipe, exist temperature to be lower than the position of previous section, by ON-OFF control rather than PID control the carrying out control of heater temperature, SiCl 4And TiCl 4The fluctuating range of the gas temperature in the pipe is more than ± 2 ℃ separately, and is supplying SiCl in burner 4And TiCl 4Be not provided with outside the unstripped gas stirring mechanism before each, use with embodiment 4 in identical mode obtain TiO 2-SiO 2Vitreum.
Embodiment 9
That Corning Incorporated makes, as zero thermal expansion TiO 2-SiO 2The known ULE#7972 of glass.
The measurement result of the physicals separately of the glass of preparation is summed up and is shown in Table 1 in the foregoing description 1 to 9.About evaluation method, measure according to the said determination method respectively.And, obtain the COT shown in the table 1 by the temperature when the curve shown in Fig. 1 determines that thermal linear expansion coefficient is 0ppb/ ℃.Temperature range when determining that from the curve shown in Fig. 1 thermal linear expansion coefficient is-5 to 5ppb/ ℃ obtains the Δ T shown in the table 1.
[table 1]
Figure BPA00001208075700221
Can know from table 1 and to find out, be among 40 to 110 ℃ of embodiment 1 to 5 in the scope at COT, thermal linear expansion coefficient is substantially zero when using the photoirradiation of high EUV energy, and in wide temperature range CTE basicly stable be zero, so the glass of these embodiment 1 to 5 is suitable as the optics of EUVL with exposure tool.
In addition, the evaluation result of the striped level of the glass of the foregoing description 1 to 9 is summed up and is shown in Table 2.Evaluation method is as follows.The surface smoothness (rms) of embodiment 1 to 5 is below the 1nm, and the surface smoothness of embodiment 8 (rms) is more than the 3nm.
[table 2]
Figure BPA00001208075700231
Can know from table 2 and to find out that with the glassy phase ratio of embodiment 6 to 9, the standard deviation of fringe stress level is that 0.03MPa is following, maximal roughness PV is that 0.2MPa is following, the fluctuating range of specific refractory power is 2 * 10 -4Although the glass TiO of following embodiment 1 to 5 2The content height, but the surface that obtained to have the very high surface smoothness, so the glass of these embodiment 1 to 5 is suitable as the optics of EUVL with exposure tool.
Embodiment 1 to 5 from table 2 can know and find out, for the standard deviation that obtains the fringe stress level below the 0.03MPa, the maximal roughness PV and 2 * 10 below the 0.2MPa -4The fluctuating range of following specific refractory power, below all three kinds of striped methods of minimizinging all be effective: (1) makes the charging stabilization of glass raw material gas when supplying glass formation raw material; (2) in the glass raw material gas feed system, stirring mechanism is installed; (3) high speed rotating seed rod.
Although describe the present invention in detail with reference to the specific embodiment of the present invention, it should be apparent to those skilled in the art that in the case of without departing from the spirit and scope of the present invention and can carry out various changes and correction to it.
The Japanese patent application 2008-044811 that the application submitted to based on February 26th, 2008 introduces it in full by reference.All reference of quoting are herein incorporated in full with it.
Industrial applicibility
TiO of the present invention2-SiO 2Glass is at the light irradiation that uses high EUV energy and temperature when raising, and the variation of comparing its size and dimension with room temperature is very little, and obtains surface with very high surface smoothness, so it is suitable as EUVL with the optics of exposure tool very much.

Claims (13)

1. one kind contains TiO 2Silica glass, the TiO of described silica glass 2Content is 7.5 to 12 quality %, and the temperature when thermal linear expansion coefficient is 0ppb/ ℃ is in 40 to 110 ℃ the scope, and is below the 0.03MPa in the zone of the 30mm * 30mm of the standard deviation of fringe stress level (σ) at least one face.
2. one kind contains TiO 2Silica glass, the TiO of described silica glass 2Content is 7.5 to 12 quality %, and the temperature when thermal linear expansion coefficient is 0ppb/ ℃ is in 40 to 110 ℃ the scope, and is below the 0.2MPa in the zone of the 30mm * 30mm of the maximal roughness of fringe stress level (PV) at least one face.
3. one kind contains TiO 2Silica glass, the TiO of described silica glass 2Content is 7.5 to 12 quality %, and the temperature when thermal linear expansion coefficient is 0ppb/ ℃ is in 40 to 110 ℃ the scope, and is 4 * 10 in the zone of the 30mm * 30mm of the fluctuating range of specific refractory power (Δ n) at least one face -4Below.
4. each described TiO that contains of claim 1 to 3 2Silica glass, the average thermal linear expansion coefficient of described silica glass in 20 to 100 ℃ of scopes is below 60ppb/ ℃.
5. each described TiO that contains of claim 1 to 4 2Silica glass, the fictive temperature of described silica glass is below 1100 ℃.
6. each described TiO that contains of claim 1 to 5 2Silica glass, described silica glass does not contain inclusion.
7. EUV photoetching optics, described optics uses each described TiO that contains of claim 1 to 6 2Silica glass.
8. the described EUV photoetching of claim 7 optics, the surface smoothness of described optics (rms) is below the 3nm.
9. each described TiO that contains of claim 1 to 6 2The manufacture method of silica glass, described method comprises:
With the silica precursor gasification,
With titanium dioxide precursor gasification and
Transport the silica precursor of gasification and the titanium dioxide precursor of gasification respectively by pipe A and pipe B, thereby to the precursor of burner supply gasification,
Wherein said pipe B is configured to have towards the direction of described burner the temperature of rising.
10. the described TiO that contains of claim 9 2The manufacture method of silica glass, wherein control described pipe B by PID, thus make its in the temperature fluctuation amplitude of each point within ± 1 ℃.
11. the described TiO that contains of claim 9 2The manufacture method of silica glass, the volumometer when being scaled normal atmosphere wherein, the gas flow rate among the described pipe B is more than 0.1 meter per second.
12. the described TiO that contains of claim 9 2The manufacture method of silica glass, further be included in the step that is supplied to before the burner each gas stirring.
13. the described TiO that contains of claim 9 2The manufacture method of silica glass, further comprise the TiO that is shaped with the regulation shape 2-SiO 2Glass shaping body kept under 600 to 1200 ℃ temperature more than 2 hours, then with the average rate of temperature fall below 10 ℃/hour temperature was reduced to step below 500 ℃.
CN2009801065551A 2008-02-26 2009-02-26 TiO2-containing silica glass and optical member for EUV lithography using high energy densities as well as special temperature controlled process for its manufacture Pending CN101959820A (en)

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